Used to denigrate the area as it is generally regarded as a poverty stricken slumhole generally inhabited by worthless people. Based on the New York's Bronx.
The term may only be used by natives of the area however to pay themselves out, particularly by those who managed to get the hell out of the place!! Use by an outsider will result in a severe kicking.
He likes Eminem, wear FUBU clothes and wads over cars; what a bronxy.
I'm heading to the Bronx.